This invention relates to a method and apparatus for manufacturing a semiconductor device, and more particularly to a method and apparatus for removing contaminants from the surface of a semiconductor wafer within the same chamber as used for film formation.
Recent progress in fineness of semiconductor devices reveals the degradation of device characteristics owing to re-growth of a natural oxide film and re-deposition of organic contaminants after cleaning of a semiconductor wafer in a manufacturing process, which has not been such a serious problem in the past.
FIG. 7 shows a diagram illustrating a conventional method and system including a cleaning apparatus and a film-forming apparatus. In a conventional semiconductor fabrication process, surface cleaning, which influences the characteristics of the device, is effected immediately before formation of films such as a gate oxide film, electrode layers, a capacitor dielectric film, etc. For this purpose, wet cleaning apparatus such as pre-diffusion treatment apparatus, light etching apparatus or the like has been generally used.
Various techniques have been proposed with regard to a cleaning apparatus or a film-forming apparatus. Examples of such proposals include those set out in Japanese Laid-open Patent Application Nos. 4-279022, 3-224222, 61-32429, 3-87373, 7-507844, 8-53767 and 61-280623.
However, in a conventional flow of a manufacturing process, wet cleaning is performed prior to a film-forming step, and a semiconductor wafer is transferred to a film-forming apparatus to form a film thereon. Therefore, it is very likely to suffer various contamination during the course of the film-forming steps after the cleaning. Such contamination may be due to a contamination suffering from an atmosphere of clean room prior to a temporary storage of a wafer in a casing, a contamination from the casing or cassette during the storage, and a contamination from an operator or a robotic system carrying the wafer to a film-forming apparatus. Further, the contamination may be caused when a wafer is transferred from a cleaning apparatus to a film-forming position in a film-forming apparatus, or when a pressure in the film-forming apparatus is reduced or a gas is fed to the apparatus.
Accordingly, it is an object of the present invention to provide a method and an apparatus for manufacturing a semiconductor device having improved reliability, and more particularly a method and an apparatus for removing contaminants on the surface of a semiconductor wafer in a film-forming apparatus immediately before film formation, by which the problems involved in the prior art techniques are overcome.
In other words, it is an object of the present invention to provide a method and apparatus which are able to suppress surface contamination during cleaning and film-forming process of a semiconductor wafer to obtain a surface or film showing good characteristics.
According to one aspect of the present invention, in a method for manufacturing a semiconductor device, a semiconductor wafer is placed in a film-forming chamber, and contaminants on the surface of the semiconductor wafer are removed in the film-forming chamber. Then, immediately after the removal of the contaminants, either a conductive film or an insulating film is formed on the surface of the wafer in the same film-forming chamber.
In another aspect of the present invention, in the method for manufacturing a semiconductor device, hydrogen gas or a hydrogen halide gas is introduced into the film-forming chamber via a flow rate control means. Then, the introduced hydrogen gas or hydrogen halide is heated in the film-forming chamber to generate hydrogen radicals in the film-forming chamber. Thus, contaminants are removed from the surface of the semiconductor wafer.
The hydrogen gas or hydrogen halide may be heated, for example, by means of a hot filament in the film-forming chamber.
In another aspect of the present invention, in the method for manufacturing a semiconductor device, hydrogen gas or a hydrogen halide gas is introduced into the film-forming chamber via a flow rate control means. Then, a plasma is generated in the film-forming chamber so that the semiconductor wafer is covered with the plasma which generates hydrogen radicals. Thus, contaminants are removed from the surface of the semiconductor wafer.
The plasma may be generated in different exciting frequencies simultaneously.
In another aspect of the present invention, in the method for manufacturing a semiconductor device, hydrogen gas or a hydrogen halide gas is introduced into the film-forming chamber via a flow rate control means. Then, the semiconductor wafer is heated from outside of the film-forming chamber. Thus, contaminants are removed from the surface of the semiconductor wafer.
The semiconductor wafer may be preferably heated at a temperature ranging from 500 to 1200xc2x0 C.
In another aspect of the present invention, in the method for manufacturing a semiconductor device, hydrogen gas or a hydrogen halide gas is introduced into the film-forming chamber via a flow rate control means. Then, the semiconductor wafer is heated from outside of the film-forming chamber. Simultaneously, a plasma is generated in the film-forming chamber so that the semiconductor wafer is covered with the plasma which generates hydrogen radicals. Thus, contaminants are removed from the surface of the semiconductor wafer.
According to another aspect of the present invention, an apparatus for manufacturing a semiconductor device comprises a film-forming chamber for forming a film on a semiconductor wafer. Means is provided for introducing hydrogen gas or a hydrogen halide gas via a flow rate control means into the film-forming chamber. Wafer heating means is provided for heating the semiconductor wafer from outside of the film-forming chamber. Thus, contaminants on the surface of the semiconductor wafer are removed.
In another aspect of the present invention, the apparatus for manufacturing a semiconductor device further comprises a load lock chamber for introducing a semiconductor wafer. The load lock chamber is connected to the film-forming chamber, and is used to transfer the semiconductor wafer to the film-forming chamber in a continuous vacuum condition.
In another aspect of the present invention, a semiconductor manufacturing system comprises a plurality of apparatuses each for removing contaminants on a surface of a semiconductor wafer and forming either a conductive film or an insulating film on said surface of said wafer in a film-forming chamber immediately after the removal of said contaminants. A transfer chamber is provided to which each of the film-forming chamber of the apparatuses is connected, and a continuous vacuum may be established therebetween. Then, a semiconductor wafer may be transferred in a continuous vacuum condition to the film-forming chamber and may be subjected to film formation.
According to another aspect of the present invention, an apparatus for manufacturing a semiconductor device comprises a film-forming chamber for forming a film on a semiconductor wafer. Means is provided for introducing hydrogen gas or a hydrogen halide gas via a flow rate control means into the film-forming chamber. Gas heating means is provided for heating the introduced hydrogen gas or hydrogen halide gas in the film-forming chamber to generate hydrogen radicals whereby contaminants on the surface of the semiconductor wafer are removed.
The gas heating means may be a hot filament.
The hot filament may comprise a metal material serving as a catalyst for hydrogen radical formation reaction.
A metal material serving as a catalyst for hydrogen radical formation reaction may be provided in the vicinity of the hot filament.
According to another aspect of the present invention, an apparatus for manufacturing a semiconductor device comprises a film-forming chamber for forming a film on a semiconductor wafer. Plasma generating means is provided which includes a pair of plasma generating electrodes disposed within the film-forming chamber, and a power supply means for supplying a high frequency voltage to the paired electrodes. Thus, a plasma is generated to form hydrogen radicals with which contaminants on the surface of the semiconductor wafer are removed.
The power supply means may supply high frequency voltages of different frequencies simultaneously.
Additional objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description, wherein only the preferred embodiment of the invention is shown and described, simply by way of illustration of the best mode contemplated for carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.